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3 years ago

What is the approximate percentage of nitrogen in the Earth's current atmosphere?

Chemistry

1 answer:

RoseWind [281]3 years ago

7 0

Answer:

78% nitrogen

Explanation:

It has been long agreed upon that our atmosphere is highly abundant with nitrogen. Our atmosphere is composed of 78% nitrogen and then other gases follow such as 21% oxygen, 0.9% argon, and 0.03% carbon dioxide with very small percentages of other elements.

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Determine whether the statement is true or false, and why. "If a theory becomes supported by evidence, it can become a law."

loris [4]

Answer: D. False, it should read, "A theory and a law are already both supported by evidence and are equal, but they have different functions."

Explanation:

A "Theory" and a'' Law" in scientific method are already both supported by evidence but they have different function,

The function of " Theory" in scientific method is to give an explanation to the observations and findings gathered during the process. It can be modified, improved or even rejected as more information is being gathered.

While a '' Law '' tends to describe an observed event in nature that is true whenever it is put to test. It does not explain why the occurence or event is true.

5 0

3 years ago

Pulverized coal pellets, which may be approximated as carbon spheres of radius ro= 1 mm, are burned in a pure oxygen atmosphere

Ganezh [65]

Answer:

Explanation:

SO; If we assume that:

P should be the diffusion of oxygen towards the surface ; &

Q should be the diffusion of carbondioxide away from the surface.

Then the total molar flux of oxygen is illustrated by :

$Na,x = - cD_{PQ}\frac{dy_P}{dr} +y_P(NP,x + N_Q,x)$

where;

r is the radial distance from the center of the carbon particle.

Since ;

$N_P,x = - N_Q, x$ ; we have:

$Na,x = - cD_{PQ}\frac{dy_P}{dr}$

The system is not steady state and the molar flux is not independent of r because the area of mass transfer $4\pi r^{2}$ is not a constant term.

Therefore, using quasi steady state assumption, the mass transfer rate $4\pi r^{2}N_{P,x}$ is assumed to be independent of r at any instant of time.

$W_{P}=4\pi r^{2}N_{P,x}$

$W_{P}=-4\pi r^{2}cD_{PQ}\frac{dy_{P}}{dr}$

= constant

The oxygen concentration at the surface of the coal particle $yP,R$ will be calculated from the reaction at the surface.

The mole fraction of oxygen at a location far from pellet is 1.

Thus, separating the variables and integrating result into the following:

$W_{P}\int_{R}^{\infty} \frac{dr}{r^{2}}=-4\pi$

$r^{2}cD_{PQ}\int_{y_{P,R}}^{y_{P,\infty }}dy_{P}$

$-W_{P}\frac{1}{r}\mid ^{\infty }_{R}= -4\pi cD_{PQ}(y_{P,\infty }-y_{P,R})$

$=> W_{P}= - 4\pi cD_{PQ}(1-y_{P,R})R$

The mole of oxygen arrived at the carbon surface is equal to the mole of oxygen consumed by the chemical reaction.

$W_{P} = 4 \pi R^2R"$

$W_{P}= 4\pi R^{2}k_{1}"C_{O_{2}}\mid _{R}$

$W_{P}= 4\pi R^{2}k_{1}"c y _{P,R}$

$-4\pi cD_{PQ}(1-y_{P,R})R= - 4\pi R^{2}k_{1}"c y _{P,R}$

$y_{P,R}=\frac{D_{PQ}}{D_{PQ}+Rk_{1}}$

$y_{P,R}=\frac{1.7 \times 10^{-4}}{1.7\times 10^{-4}+10^{-3}\times 0.1}$

$\mathbf{= 0.631}$

Obtaining the total gas concentration from the ideal gas law; we have the following:

where;

R= $0.082m^3atm/kmolK$

$c=\frac{P}{RT} \\ \\ c=\frac{1}{0.082\times 1450} \\ \\ = 0.008405kmol/m^3$

The steady state $O_2$ molar consumption rate is:

$W_{P}= -4\pi cD_{PQ}(1-y_{P,R})R$

$W_{P}= -4\pi (0.008405)(1.7\times 10^{-4})(1-0.631)(10^{-3})$

$W_{P}= - 6.66\times 10^{-9}kmol/s$

5 0

3 years ago

Which of the following are accurate descriptions of closed and open thermodynamic processes? open processes are 'flow through' p

Shalnov [3]

Answer: Option (a) is the correct answer.

Explanation:

According to thermodynamics, a closed system is defined as the system in which there will be no exchange of matter takes place but there will be exchange of energy between the system and surrounding.

On the other hand, an open system is defined as the system in which there will be exchange of both matter and energy takes place between system and surrounding.

Hence, we can conclude that out of the given options accurate descriptions of closed and open thermodynamic processes is that open processes are 'flow through' processes.

7 0

3 years ago

How many atoms are in a sample of 68.7 g copper (Cu)?

dlinn [17]

Divide the number of grams present in the sample by copper's gram atomic weight to find the number of gram atomic weights present. Then multiply that result by Avogadro's Number: 6.022137 x 10^23 atoms/gram atomic weight.1,200 g/(63.54 g/gram atomic weight) ? 18.885741 gram-atomic weights. Hope this helps.

8 0

4 years ago

Read 2 more answers

Writing a pressure equilibrium constant expression Ammonia and oxygen react to form nitrogen monoxide and water, like this: 4 NH

Sliva [168]

Answer: The equilibrium constant expression for the given equation is written below.

Explanation:

Equilibrium constant in terms of partial pressure is defined as the ratio of partial pressures of products to the partial pressures of reactants each raised to the power their stoichiometric ratios. It is expressed as $K_{p}$